1. Field of the Invention
This invention relates to automatic coffee-brewing machines and, more particularly, to an improved heating and control system for such systems.
2. Description of the Prior Art
In coffee brewing machines such as percolators and, particularly, drip coffeemakers having a hot water pump apparatus, it has long been the practice to sense the temperature of the pump apparatus, and the water therein, and disconnect the pump heater as soon as a predetermined temperature has been reached. At this point the brewing operation is complete. Since this sensing and switching is normally done by means of a thermostatic switch closely associated with the heater, subsequent cooling of the pump assembly could cause the heater to be reenergized again. To prevent such an occurrence, it has been common to provide another heater for maintaining, upon completion of the brewing cycle, the pump assembly at a temperature high enough to prevent reinitiation of the brewing cycle. It has also been common in the prior art to provide a separate heater for maintaining the brewed coffee at serving temperature following completion of the brewing cycle. In drip coffeemakers, these "keep warm" heaters typically heat the coffee carafe at a relatively low energy level both during and subsequent to the brewing cycle. These arrangements have not been altogether satisfactory in that the initial heat output when starting with a cold carafe may not be sufficient to prevent undue cooling of the coffee.